Method for electrolytically producing a metal band

ABSTRACT

THE METHOD RESIDES IN DEPOSITING THE METAL ELECTROLYTICALLY ON THE SURFACE OF A CATHODE FROM AN ELECTROLYTIC SOLUTION, WITH THE CURRENT DENSITY BEING SUCCESSIVELY VARIED IN A PLURALITY OF STAGES: DURING THE FIRST ONES OF THESE STAGES THE CURRENT DENSITY IS MAINTAINED WITHIN A RANGE FROM 1,000 TO 5,000 A./SQ. M., DURING THE LAST STAGE BUT ONE THE CURRENT DENSITY IS MAINTAINED WITHIN A RANGE FROM 5,000 TO 10,000 A./SQ. M. FOR A PERIOD FROM 1 SECOND TO 300 SECONDS, DURING THE LAST STAGE THE CURRENT DENSITY IS MAINTAINED WITHIN A RANGE FROM 4,000 TO 50,000 A./SQ. M. FOR A PERIOD FROM 1 SECOND TO 200 SECONDS, THE ELECTROLYTIC SOLUTION BEING POSITIVELY AGITATED DURING ALL SAID STAGES EXCEPT THE LAST ONE. THE APPARATUS COMPRISES AT LEAST THREE ANODE PLATES ARRANGED ABOUT THE PERIPHERY OF THE CATHODE DRUM AND RAIDIALLY SPACED THEREFROM WITHIN THE BATH CONTAINING THE ELECTROLYTIC SOLUTION, THE ANODE PLATES BEING CONNECTED TO THE INDIVIDUAL POWER SUPPLY SOURCES. THE TWO ANODE PLATES, WHICH ARE THE LAST ONES IN THE DIRECTION OF THE PROGRESS OF THE METAL BAND, HAVE THE RATIO OF THE RESPECTIVE SURFACE AREAS THEREOF WITHIN A RANGE FROM 15:1 TO 5:1. THE INTERELECTRODE SPACE, PERTAINING TO THE LAST ONE OF THESE ANODE PLATES, IS SEPARATED BY A PARTITION FROM THE REST OF THE INTERNAL SPACE OF THE BATH.

Maw}! 26, 1974 A. VLADIMIROVNA ETA!- $1 METHOD FOR EQE'JTROLYTICALLYPRODUCING A METAL BAND Filed May 9, 1972 United States Patent 3,799,847METHOD FOR ELECTROLYTICALLY PRODUCING A METAL BAND AntoninaVladimirovnaBuzhinskaya, Murmansky proezd 6, kv. 54; Leonid Alexandrovich Sergeev,prospekt Miro 34, kv. 2; Vladimir Ivanovich Trofimov, Neglinnaya ulitsa17, kv. 29; Vyacheslav Borisovich Bobrov, Yaroslavskaya ulitsa 1/9, kv.30; Anna Iliuichna Migina, B. Spasskaya ulitsa 36/2, kv. 5; and TatyanaFedorovna Perelygina, Vorgtnikovsky perevlok 11, kv. 31, all of Moscow,U.S.S.R.; and Anatoly Borisovich Bobrov, deceased, late of Moscow,U.S.S.R.; by Evodika Nikolaevna Bobrova, ulitsa Arbat 51, kv. 117; andIrina Maximovna Bobrova, Konkovo-Derevlevo 1, mikroraion, korpus 4, kv.118, both of Moscow, U.S.S.R., administrators Filed May 9, 1972, Ser.No. 251,737 Int. Cl. C23b 7/02, .7/04; B01k 3/02 U.S. Cl. 204-13 1 ClaimABSTRACT OF THE DISCLOSURE The method resides in depositing the metalelectrolytically on the surface of a cathode from an electrolyticsolution, with the current density being successively varied in aplurality of stages: during the first ones of these stages the currentdensity is maintained within a range from 1,000 to 5,000 a./sq. m.,during the last stage but one the current density is maintained within arange from 5,000 to 10,000 a./sq. rn. for a period from 1 second to 300seconds, during the last stage the current density is maintained withina range from 4,000 to 50,000 a./sq. rn. for a period from 1 second to200 seconds, the electrolytic solution being positively agitated duringall said stages except the last one.

The apparatus comprises at least three anode plates arranged about theperiphery of the cathode drum and raidially spaced therefrom within thebath containing the electrolytic solution, the anode plates beingconnected to the individual power supply sources. The two anode plates,which are the last ones in the direction of the progress of the metalband, have the ratio of the respective surface areas thereof within arange from 1511 to 5:1. The interelectrode space, pertaining to the lastone of these anode plates, is separated by a partition from the rest ofthe internal space of the bath.

The invention relates to methods of production of metal bands and toapparatus for accomplishment of such methods, which are used innon-ferrous metallurgy, in the electronics industry and in electricalengineering for the manufacture of thin metal bands.

Widely known in the art is a method of producing a metal band bydepositing the metal electrolytically from an elecrtolytic solution onthe surface of the cathode, with the current density above 1,000 amperesper square metre, with the electrolytic solution being positivelyagitated, and an apparatus employing this method, comprising a bathcontaining the electrolytic solution, incorporating barbotage means foragitating this solution, this bath having mounted interiorly thereof acathode drum and a plurality of anode plates mounted about the peripheryof said drum.

The metal band produced by the above known method and apparatus has asmooth side contacting the cathode and the opposite side which is mat,the surface of this opposite side being unsufiiciently developed.

Such band cannot be used for the manufacture of dielectric articlesWithout additional treatment in a specially designed apparatus, sincethe strength of its adhesion to the dielectric layer proves to beinsuflicient.

A disadvantage of the known methods and apparatus 3,799,847 PatentedMar. 26, 1974 ice for production of metal bands of the kind referred tois also the necessity of additionally re-winding the band, which resultsin repeated breakages of the band, whereby the yield of quality productis brought down.

It is an object of the present invention to provide a method ofproducing a metal band and an apparatus for accomplishment of thismethod, which should be capable of producing the metal band and ofhaving one side of this band treated on a single cathode.

With this object in view, the invention resides in a method of producinga metal band by depositing the metal electrolytically from anelectrolytic solution on the surface of a cathode with the currentdensity being above 1,000 amperes per square metre and with saidelectrolytic solution being positively agitated, in which method, inaccordance with the invention, said process of electrolytic depositionis performed with a single cathode, with the current density beingsuccessively varied in a plurality of stages, said current density beingmaintained during the first ones of said plurality of stages within arange from 1,000 amperes per square metre to 5,000 amperes per squaremeter, said current density being maintained during the stage precedingthe final one of said stages Within a range from 5,000 to 10,000 amperesper square metre for a period from 1 second to 300 seconds, said currentdensity being maintained during said final stage within a range from4,000 to 50,000 amperes per square metre for a period from 1 second to200 seconds, said electrolytic solution being positively agitated duringall said stages except said final one. In this way it has becomepossible to produce a metal band having one side thereof smooth and theother side thereof rough with a highly developed surface, providing forsufiicient strength of adhesion to a dielectric layer.

For accomplishment of this method, there has been provided an apparatuscomprising a bath containing the electrolytic solution, said bathincorporating barbotage means for agitating said electrolytic solution,and a cathode drum mounted interiorly of said bath, at least three anodeplates being mounted interiorly of said bath about the periphery of saidcathode drum, in which apparatus, in accordance with the presentinvention, said anode plates are electrically connected to theirrespective individual power supply sources, the two of said anodeplates, which are the last ones in the direct of the progress of saidmetal band, having the ratio of the respective surface areas thereofwithin a range from 15:1 to 5:1 the inter-electrode space within saidband, pertaining to said anode plate which is the last one in thedirection of the progress of said metal band, being separated from therest of the internal space of said bath by a partition means.

Thus it has become possible to obtain a required metal band and to haveone of the sides thereof treated to a desired effect within a singleapparatus on a single cathode.

Given below is a detailed description of an embodiment of the invention,with reference being had to the accompanying drawings, wherein:

FIG. 1 is a cross-sectional schematic view of an apparatus embodying theinvention;

FIG. 2 is a sectional view taken along line IIII of FIG. 1.

Referring now in particular to the appended drawings, the apparatuscomprises a metal housing 1 (FIG 1) consisting of two all-weldedtitanium semi-cylinders, the housing also acting as an electrolyticbath. Positioned interiorly of this bath is a cathode drum 2. Positionedabout the periphery of the cathode drum 2 and radially spaced therefromare anode plates 3, 4, 5 and 6. The anode plate 3, which is the firstone in the direction of the progress of the band 7, is secured on thefirst one of the two semi-cylinders making up the housing 1, while theanode plates 4, and 6 are secured in succession on the other one of thetwo semi-cylinders. The anode plates 3 and 4 are connected to a commonsource of power supply, and the anode plates 5 and 6 are connected,respectively, to their individual-diflierent sources of power supply,whereby the two last-mentioned anodes are mounted on the housing 1 withthe insulating members 8 and 9, respectively, interposed therebetween.The apparatus is provided with barbotage means 10 for agitating theelectrolyte in the bath with the help of air streams. Manifolds 11 aredisposed in the bottom portion of the housing 1 for introduction of theelectrolyte into the housing, while overflow pockets 12 are provided inthe upper portion of the housing 1, through which the electrolyte leavesthe bath. The air and the anode gases are withdrawn from the internalspace of the housing 1 through exhaust ventilation pipes 13. The cathodedrum 2 is journalled for rotation in bearings 14 (FIG. 2) and isimparted rotation by an appropriate drive mechanism (not shown in theappended drawings). To prevent deposition of copper on the end faces ofthe cathode drum 2, these end faces are protected with rings 15 madefrom an acid-resistant dielectric material. The rings are secured inspring-biased end covers 16. Annular diaphragms 17 are interposedbetween the end covers 16 and the respective ends of the housing 1.

To facilitate mounting, dismantling, inspection and routine maintenanceof the apparatus, the left-hand and the right-hand semi-cylinders of thehousing 1 can be easily swung aside from the cathode drum 2, thesemicylinders in this case being pivoted about a pivot axis 18 with thehelp of the respective actuators 19.

The herein disclosed apparatus is supplied with electric power fromthree different current sources, the respective negative poles of thethree sources being jointly connected electrically to the cathode drum 2through brush contacts 20, whereas the positive poles of the threecurrent sources are individually connected with the re spective ones ofthe anode plates. As it has been mentioned hereinabove, the firstcurrent supply source supplies current to the anodes 3 and 4, the secondcurrent supply source supplies current to the anode plate 5, and thethird current supply source supplies current to the anode plate 6. Inthe direction of the progress of the band 7 each successive anode platehas the surface area which is smaller than that of the preceding anodeplate. This feature of the herein disclosed apparatus is explained, asfollows: the anode plates 3 and 4 are intended for formation of themetal band, as such; the anode plate 5 is intended to ensure sufiicientroughness of the surface of this metal band, while the anode plate 6thelast in the successionis intended to ensure formation of an adhesionlayer with a highly developed surface on the rough side of the band. Thesurface areas of the respective anode plates is determined by the timeneeded for each one of the abovementioned processes. For example, when amicron thick metal band is produced, the ratio of the surface areas ofthe two anode plates 5 and 6, which are the last ones in the directionof the progress of the band, equals (15 to 5):l.

The inter-electrode space pertaining to the anode plate 6 which is thelast one in the direction of the progress of the metal band 7 isseparated from the rest of the internal space of the bath by an elasticpartition 21 slidingly engaging the periphery of the cathode drum 2, thepartition being made from a resilient dielectric materia The hereindisclosed apparatus operates, as follows.

The electrolyte is introduced into the bath through the inlet manifold11. Air is supplied through the barbotage means10 to agitate theelectrolyte, and the power supply to the anode plates 3, 4 and 5 isswitched on, with the cathode drum 2 kept immovable. Anappropriate timeis given under these conditions for a layer of met l t be deposited onthe cathode drum 2. Then the drive imparting rotation to the cathodedrum 2 is engaged. As the cathode drum 2 thus set into rotation, themetal deposit in the form of a band advancing from the electrolyte isseparated from the surface of the cathode drum 2 and is threaded over aguiding roller 22. Thereafter the power supply to the anode plate 6 isswitched on, to apply an adhesion layer on the metal cathode depositbeing formed.

The metal deposit is primarily formed on the cathode drum 2 adjacent tothe anode plates 3 and 4, the current density being from 1,000 a./sq. m.to 5,000 a./sq. m.; then, as the cathode drum with the metal depositthereon passes adjacent to the anode plate 5, the respective currentdensity in this area is maintained within a range from 5,000 a./sq. m.to 10,000 a./sq. m. (i.e. the density here approaches the criticalvalue), and thus within a period from 1 second to 300 seconds theexposed surface of the metal deposit acquires the necessary roughness.As the cathode drum 2 rotates further on, the metal deposit enters thezone adjacent to the anode plate 6, separated from the rest of theinternal space of the bath by the partition 21. Here, in the spacebetween the anode plate 6 and the cathode drum 2, the current density ismaintained within a range from 4,000 a./sq. m. to 50,000 a./sq. m. (i.e.above the critical value), and thus Within a period from 1 second to 200seconds there is deposited an adhesion layer which is an electrolyticdeposit with a highly developed surface. This final stage of theprocessing of the surface of the metal deposit takes place in the zonewhere the electrolyte is relatively calm, i.e. where the electrolyte ispractically not agitated.

In operation of the herein disclosed apparatus the electrolyte iscontinuously recirculated. The interelectrode space pertaining to theanode plate 6 communicates with the general volume of the electrolytethrough the overflow outlet pocket 12 and also through the gaps (notshown) left between the ends of the partition 21 and the respective onesof the two end covers 16.

The above described method can be employed for production of a metalband within a wide range of thicknesses, for example, from 10 microns to110 microns. The required thickness of the metal band being produced isobtained by selecting the appropriate speed of the rotation of thecathode drum 2.

EXAMPLE 35 micron thick metal band is produced, as follows. Copper bandis deposited onto the titanium cathode drum from sulfuric acidbasedelectrolyte containing 250 to 275 grams per litre of blue vitriol(sulfuric copper) and 70 to grams per litre of free sulfuric acid, at atemperature of 35 C., and air agitation, the current density being 2,500a./sq. m. (the anode may be either a soluble one, or a non-soluble one).

The duration of the first stage, i.e. of the deposition stage, is 6minutes 27 seconds. Then the second stage is commenced. During thisstage the above conditions of the electrolysis are maintained the same,but the current density is increased to 5,000 a./sq. m., i.e. to thevalue approach in the critical one. During the third stage of theprocess the electrolyte is no longer agitated, and the current densityis increased to a value above the critical one, i.e. to 7,500 a./sq. m.The duration of the third stage is 1.5 seconds.

When the above described process is completed, the band is removed fromthe cathode, washed and dried. The foil thus obtained is ready formanufacture of materials incorporating copper foil.

Materials incorporating the copper band thus obtained have displayedstability of the strength of the adhesion of the band to the dielectriclayer, both over the delivery period and after having been tested forgalvanic stability, thermal stability and resistance to moisture, unlikeoxidized band which is apt to have the strength of the adhesionconsiderably afiected by such tests (see Table 1 said final stage thecurrent density is maintained within a hereinbelow). range from 4,000amperes per square metre to 50,000

TABLE 1 Adhesion strength, grams/em.

Atter Delivered After exposure After in the Alter exposure to 95%exposure state galvanic to 180 C. humidity to 265 C. manuiecstabilityduring for 48 for Sample of band-incorporating material, NED-type tm'etest 100 hours hours seconds Band obtained by the herein disclosedmethod, 35 micron thick 1,640 1, 600 1,475 1, 620 1, 925 Oxidized hand1,650 1,100 100-200 Permissible value, not below 1, 500 700 800 1,000

The herein disclosed method of producing metal band amperes per squaremetre; said electrolytic solution being and the apparatus employing thismethod make it possible positively agitated during all said stagesexcept said final to obtain metal band of which one side can becontinuone. ously processed within a single apparatus. References CitedWhat UNITED STATES PATENTS 1. Method of producing a metal band havingone side thereof rough and provided on its rough side with an ad-3,674,656 7/1972 Yates hesion layer having a highly developed surface,compris- 3,293,109 12/1966 Luce et 204-52 ing the step of depositingelectrolytically the metal from FO GN PATENTS an electrolytic solutiononto the surface of a single cath- 18,870 5/1961 Japan 204 12 ode, withthe current density being successively varied in a plurality of stages:during the first ones of said stages the current density is maintainedwithin a range from JOHN MACK Pnmary Exammer 1,000 to 5,000 amperes persquare metre, during the stage T. TUFARIELLO, Assistant Examinerpreceding the final stage the current density is maintained within arange from 5,000 to 10,000 amperes per square US. Cl. X.R. metre for aperiod from 1 second to 300 seconds; during 204-208, 231

